It just occurred to me that Kohlberg's theory of moral development would apply to both Kat's kids and mine. The "I'm doing it so I get a reward" or "I'm not doing it so I avoid punishment" is lovely level one—completely age appropriate. I find this reassuring.

I try to remember to stay age appropriate in my negotiations.

David: more toothpaste!
Mommy: That's enough.
David: Why?
Mommy: Because the dentist said so.

We have gotten into a whole discussion of how too much toothpaste makes you throw up, but sometimes "the outside authority said so" is right for this level of development.

I just can't remember what Kohlberg said about how to move them to the next stage.